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Biomedical subjects

C Shy

Publications and source records attributed to C Shy.

At least 19 recordsLinked to original sources
PubMed2003

Health consequences associated with frequent wheezing in adolescents without asthma diagnosis.

Using questions from the International Study of Asthma and Allergies in Childhood, this study evaluated the association between undiagnosed frequent wheezing and health consequences in adolescents. The North Carolina School Asthma Survey provided self-reported questionnaire data on respiratory health from 122,829 children aged 12-14 yrs. The frequency of health consequences were compared among undiagnosed frequent wheezers, diagnosed asthmatics, and children with no wheezing symptoms or diagnosed asthma. The odds of wheezing-related sleep disturbances, limited activities, and missed school were higher among undiagnosed frequent wheezers, relative to diagnosed asthmatics. The frequency of emergency room visits and hospitalisations did not differ substantially between the undiagnosed wheezing and diagnosed asthma groups, though the undiagnosed group was less likely to have visited a physician for wheezing in the past year. Children with frequent wheezing symptoms but no asthma diagnosis experience substantial illness-related morbidity similar to that of diagnosed asthmatics. Undiagnosed frequent wheezers require more recognition from primary care physicians and need active disease management to reduce health consequences.

Absenteeism↗
PubMed2000

Asthma inhaler use and barriers in a population-based sample of African-American and white adolescents.

BACKGROUND: There is little information on inhaler medication and barriers to use among a population-based sample of adolescents and whether possible variations in asthma treatment by ethnic group exist. OBJECTIVE: We describe the prevalence of inhaler use and identify barriers for proper use of asthma medication in a population-based sample of adolescents of which 34% are African-American. METHODS: A cross-sectional survey using the ISAAC (International Survey of Asthma and Allergies in Children) questionnaire was conducted in a school population-based sample (n = 2056) of 13 to 14-year-old eight grade students in the Charlotte-Mecklenburg, North Carolina public school system. Questions were asked about symptom prevalence, asthma diagnosis, inhaler use, and barriers to care. RESULTS: Fourteen percent of the children (296/2056) reported using an inhaler in the last 12 months with no differences among African-American children and white children. Twenty-six percent of inhaler users were not allowed to carry their medication on their person while at school. Girls were more likely to be allowed to carry their inhalers at school and diagnosed asthmatic girls had a higher prevalence of wheezing in the last year (47%) compared with diagnosed asthmatic boys (35%). Smoking prevalence was higher in inhaler users (26%) compared to the study population (19%). CONCLUSIONS: Inhaler use is high in this population. Adolescents using inhalers need to reduce their smoking levels. Schools need to reevaluate their policies on the use of inhalers at school.

Adolescent↗
PubMed2000

Statewide adolescent asthma surveillance.

We assessed the prevalence of diagnosed asthma, wheezing, healthcare utilization, and environmental triggers in children ages 13-14 years, and evaluated the feasibility of statewide asthma surveillance in North Carolina. A cross-sectional study (N = 1,596) was conducted using the International Survey for Asthma and Allergies in Childhood (ISAAC) questionnaire. Ten percent reported current diagnosed asthma. Nineteen percent reported wheezing symptoms with no diagnosis of asthma. Children with frequent wheezing were more likely to be poor, African-American, and female. Thirty percent of diagnosed asthmatics made 1 or more emergency room visits in the last year. Undiagnosed asthmatics were unmedicated. These results highlight the magnitude of the asthma epidemic in early adolescence, and illustrate that statewide surveillance using ISAAC is feasible.

Adolescent↗
PubMed1999

Daily variation of particulate air pollution and poor cardiac autonomic control in the elderly.

examined the cardiac autonomic response to daily variations in PM in 26 elderly (mean age 81) individuals for 3 consecutive weeks. Several standardized methods were used to measure 24-hr average PM concentrations prior to the clinical test inside (indoor PM2.5) and immediately outside (outdoor PM2.5 and PM2.5-10) of participants' residences. Resting, supine, 6-min R wave to R wave (R-R) interval data were collected to estimate high frequency (0.15-0.40 Hz) and low frequency (0.04-0.15 Hz) powers and standard deviation of normal R-R intervals (SDNN) as cardiac autonomic control indices. Participant-specific lower heart rate variability days were defined as days for which the high-frequency indices fell below the first tertile of the individual's high-frequency distribution over the study period. Indoor PM2.5 > 15 microg/m3 was used to define high pollution days. Results show that the odds ratio (95% confidence interval) of low heart rate variability high frequency for high (vs. not high) pollution days was 3.08 (1.43, 6.59). The ss-coefficients (standard error) from mixed models to assess the quantitative relationship between variations in indoor PM2.5 and the log-transformed high frequency, low frequency, and SDNN were: -0.029 (0.010), -0.027 (0.009), and -0.004 (0.003), respectively. This first study of cardiac autonomic control response to daily variations of PM2.5 indicates that increased levels of PM2.5 are associated with lower cardiac autonomic control, suggesting a possible mechanistic link between PM and cardiovascular disease mortality.

Aged↗
PubMed1996

Review of occupational lung carcinogens.

Lung cancer is the most common malignancy in the United States and is ranked second only to bladder cancer in the proportion of cases thought to be due to occupational exposures. We review the epidemiology of occupational lung cancer, focusing on agents identified as pulmonary carcinogens by the International Agency for Research on Cancer. We derive estimates of overall relative risks from the major studies of these lung carcinogens, and we also provide estimates of the number of exposed workers. Using our data as well as estimates from other authors, we estimate that approximately 9,000-10,000 men and 900-1,900 women develop lung cancer annually in the United States due to past exposure to occupational carcinogens. More than half of these lung cancers are due to asbestos. This estimate is likely conservative, in that we have restricted our analysis to confirmed lung carcinogens and have ignored occupations with documented excess risk but for which the specific agents are unknown. Also, our estimate of the proportion of workers exposed in the past is probably too low. Our estimate should be viewed only as broad approximation. Nevertheless, it is in line with other estimates by authors using different methods. The current number of cases estimated to be due to occupational exposure reflects past high exposures and is likely to drop in the future, unless other occupational lung carcinogens are confirmed or new carcinogens are introduced into the workplace.

Acrylonitrile↗
PubMed1995

Silicosis and lung cancer among workers in North Carolina dusty trades.

In 1940-1983, 760 cases of silicosis were identified among male North Carolina (NC) workers in dusty trades. Vital status was ascertained through 1983 for 714 silicotics, and death certificates were obtained for 546 of the 550 decedents. The standardized mortality ratio (SMR) for lung cancer based on United States rates was 2.6 [95% confidence interval (95% CI) 1.8-3.6] for whites, 2.3 (95% CI 1.5-3.4) for whites unexposed to other known occupational carcinogens, and 2.4 (95% CI 1.5-3.6) for whites with no other exposure and diagnosed with silicosis while still employed in dusty trades. In addition, the age- and smoking-adjusted rate for silicotics was 3.9 times higher (95% CI 2.4-6.4) than that of nonsilicotic metal miners. This analysis effectively controlled for confounding by age, cigarette smoking, exposure to other occupational carcinogens, and detection bias. The results congrue with the hypothesis of an association between silicosis and lung cancer.

Confidence Intervals↗
PubMed1992

Reevaluation of silicosis and lung cancer in North Carolina dusty trades workers.

We previously reported on the lung cancer mortality through 1983 of 760 males who were diagnosed with silicosis during 1930-1983 by the State of North Carolina's medical examination program for dusty trades workers. The lung cancer SMR (95% confidence interval) was 2.6 (1.8-3.6) among 655 white members of this group. In this paper, we report the results of a reanalysis of mortality among a subgroup for whom chest radiographs were currently available for rereading. Technically acceptable radiographs were available for 306 white males and were independently reclassified for pneumoconiosis by 3 "B" readers using the 1980 ILO Classification. Lung cancer SMRs were 1.7 (0.8-3.1) for the entire group of 306 white males, 2.5 (1.1-4.9) for 143 subjects reclassified as simple silicosis, and 1.0 (0.1-3.5) for 96 subjects whose radiographs were reclassified as ILO category 0. There were no lung cancer deaths among 67 subjects whose radiographs were reclassified as progressive massive fibrosis. Corresponding lung cancer SMRs for subjects who had never been employed in a job with exposure to known occupational carcinogens were 1.2 (0.2-4.4) for those reclassified as category 0, and 2.4 (1.0-5.0) for those reclassified as having simple silicosis. The age-adjusted lung cancer rate ratio among subjects with simple silicosis compared to those with category 0 was 1.5 (0.4-5.8). Our findings from this reanalysis, which effectively controls for misclassification of silicosis due to errors in radiograph interpretation by North Carolina program readers, offer additional evidence consistent with the hypothesis of an association between silicosis and lung cancer in this study group.

Adult↗
PubMed1991

Silicosis and lung cancer in North Carolina dusty trades workers.

Since 1940, 760 cases of silicosis have been diagnosed as part of the State of North Carolina's (NC) pneumoconiosis surveillance program for dusty trades workers. Vital status was ascertained through 1983 for 714 cases that had been diagnosed since 1940 and death certificates were obtained for 546 of the 550 deceased. Mortality from tuberculosis, cancer of the intestine and lung, pneumonia, bronchitis, emphysema, asthma, pneumoconiosis, and kidney disease was significantly increased in whites. Mortality from tuberculosis, ischemic heart disease, and pneumoconiosis was significantly increased in non-whites. The standardized mortality ratio (95% CI) for lung cancer based on U.S. rates was 2.6 (1.8-3.6) in whites, 2.3 (1.5-3.4) in those who had no exposure to other known occupational carcinogens, and 2.4 (1.5-3.6) in those who had no other exposure and who had been diagnosed for silicosis while employed in the NC dusty trades. Age-adjusted lung cancer rates in silicotics who had no exposure to other known occupational carcinogens were 1.5 (.8-2.9) times higher than that in a referent group of coal miners with coalworkers' pneumoconiosis (CWP) and 2.4 (1.5-3.9) times higher than that in a referent group of non-silicotic metal miners. Age- and smoking-adjusted rates in silicotics were 3.9 (2.4-6.4) times higher than that in metal miners. This analysis effectively controls for confounding by age, cigarette smoking, and exposure to other known occupational carcinogens, and it is unlikely that other correlates of silica exposure could explain the excess lung cancer mortality in the silicotics.

Adult↗
PubMed1991

Demographic and health characteristics of participants and nonparticipants in a work site health-promotion program.

Work site health-promotion programs represent an increasingly common attempt by industry to improve the health of employees. The potential impact of programs is limited by nonparticipation, especially among demographic subgroups and those who could most benefit from health behavior change. The present study prospectively examined the relationship of personnel data and self-reported health habits and health status to participation in the health-promotion program at a research and development work site. Thirty-four percent of the 505 employees enrolled in the health-promotion program. White employees were 2.47 times as likely to participate as nonwhites (95% confidence interval, 1.59, 3.83). Those with health maintenance organization health insurance were 1.43 times as likely to participate as were employees with fee-for-service insurance (1.11, 1.84). There was no difference between participants and nonparticipants in self-reported health status, and only slightly more positive health habits were noted among participants. Seatbelt use was 1.65 times more common among participants (1.10, 2.49). The study results are reassuring that such programs do not enroll only the very healthy or those with healthy habits. However, the diminished enrollment of nonwhite employees supports concern that health-related programs may not equally reach all segments of the work force.

Adult↗
PubMed1990

Epidemiologic evidence on the relationship between formaldehyde exposure and cancer.

Over 30 epidemiologic studies have evaluated cancer risks associated with formaldehyde exposure. Excesses were reported for several sites, leukemia and cancers of the nasal cavities, nasopharynx, lung, and brain generating the greatest interest. The excesses of leukemia and brain and colon cancer found among professionals may not be related to formaldehyde exposure, since similar excesses were not observed among industrial workers. Inconsistencies among and within studies impede assigning formaldehyde a convincing causal role for the excesses of lung cancer found among industrial workers. A causal role for formaldehyde is the most probable for cancers of the nasopharynx and, to a less extent, the nasal cavities. Evidence of exposure-response relationships, the fact that direct contact with formaldehyde may occur at these upper respiratory sites, and the consistency of these findings with experimental studies make this assumption highly probable.

Brain Neoplasms↗
PubMed1987

The healthy worker effect in actively working communications workers.

The healthy worker effect is examined in a large population of actively working communications workers. The mortality experience of 338,306 white male workers at the American Telephone and Telegraph Company grouped by age, duration of service, and general cause categories is compared with the mortality experience of US white males in 1976. Observed were statistically significant and often substantial deficits in mortality among these active workers in almost all categories. For cancers and cardiovascular diseases, mortality ratios tended to decrease across age in the subgroups with longer service durations; these ratios consistently increased across duration of service in older ages. In subgroups with long service durations, the secondary selection of the healthy worker effect in this active worker population appears to increase with increasing age.

Adult↗
PubMed1986

Time-related factors as potential confounders and effect modifiers in studies based on an occupational cohort.

Time-related factors which are potential confounders and effect modifiers in studies based on an occupational cohort are reviewed. The most frequently considered ones include age at first exposure, duration of exposure, interval from exposure to disease recognition, and age at risk. These factors are related to the "healthy worker effect," which appears to be more pronounced among workers with the longest durations of employment and older ages, at date of hire, but weaker with longer length of follow-up and older age at risk. Hence, use of an internal comparison group may not eliminate bias since confounding will occur if the exposed and unexposed groups differ in their distributions across these factors. It is also shown, using the multistage model of carcinogenesis, that these factors may be important effect modifiers. Fortunately, generally straightforward methods of control exist both for stratified analyses and for the commonly used mathematical modeling approaches. Although no firm recommendations can be made, it would appear to be important to control for length of follow-up in the design or analysis of most studies based on an occupational cohort, and controlling for age at first exposure may also be desirable under many circumstances.

Adult↗
PubMed1981

Effect of air pollution on chronic respiratory disease in the New York city metropolitan area, 1972.

The effect of air pollution on chronic respiratory diseases (CRD) was examined in a study in the New York metropolitan area in 1972. Four study communities, sites A, B, C and D, were selected for the similarity of socioeconomic and demographic characteristics. Historically, these communities represented an increasing gradient of air pollution levels. However, after air quality improvement in the metropolitan area, Site A had only slightly lower pollution levels than sites B, C and D. In the examination of chronic respiratory symptoms, study hypotheses were established to correspond with historical levels of air pollution. The study population was drawn from parents of children attending elementary school in each site. Information was obtained by means of a questionnaire modified from the 1966 BMRC questionnaire. The analysis was based on 5416 white long-term residents without occupational exposure to irritant dust and fumes. Confounding factors, including smoking status, age, level of education of head-of-household and crowding within the home, were examined. Smoking was found to be the most important factor in determining the level of severity of CRD. The effect of air pollution showed differential patterns among the smokers and nonsmokers. Among the smokers, no air pollution effect was observed. However, among nonsmokers, a statistically significant difference was observed among females. Further, among male nonsmokers a similar pattern was observed, but the effect was not statistically significant. Other possible factors that could contribute to the difference are discussed.

Adolescent↗
PubMedDate not supplied

Particulate matter and heart rate variability among elderly retirees: the Baltimore 1998 PM study.

This study investigates the relationship between ambient fine particle pollution and impaired cardiac autonomic control in the elderly. Heart rate variability (HRV) among 56 elderly (mean age 82) nonsmoking residents of a retirement center in Baltimore County, Maryland, was monitored for 4 weeks, from July 27 through August 22, 1998. The weather was seasonally mild (63-84 degrees F mean daily temperature) with low to moderate levels of fine particles (PM2.5 < 50 micrograms/m3). Two groups of approximately 30 subjects were examined on alternate days. A spline mixed-effects model revealed a negative relationship between outdoor 24-h average fine particulate matter (PM2.5) and high-frequency (HF) HRV that was consistent with our earlier Baltimore study for all but 2 days. These 2 days were the only days with significant precipitation in combination with elevated PM2.5. They were also unusual in that back-trajectory of their air masses was distinctly different from those on the other study days, emanating from the direction of rural Pennsylvania. Mixed-effects analysis for all 24 study days showed a small negative association of outdoor PM2.5 with HF HRV (-0.03 change in log[HF HRV] for a 10 micrograms/m3 increment in PM2.5) after adjustment for age, sex, cardiovascular status, trend, maximum temperature, average dew point temperature, random subject intercepts, and autocorrelated residuals. After excluding study days 4 and 5, this association was strengthened (-0.07 change in log[HF HRV] for 10 micrograms/m3 PM2.5, 95% CI -0.13 to -0.02) and was similar to that obtained in an earlier study (-0.12 change in log[HF HRV] for a 10 micrograms/m3 increment in outdoor PM2.5, 95% CI -0.24 to -0.00) [Liao D., Cai J., Rosamond W.D., Barnes R.W., Hutchinson R.G., Whitsel E.A., Rautaharju P., and Heiss G. Cardiac autonomic function and incident coronary heart disease: a population-based case-cohort study. The ARIC Study. Atherosclerosis Risk in Communities Study. Am J Epidemiol 1997: 145 (8): 696-706]. Acute (1 to 4 h) previous PM2.5 exposure did not have a stronger impact than the 24-h measure. A distributed lag model incorporating the six preceding 4-h means also did not indicate any effect greater than that observed in the 24-h measure. This study is consistent with earlier findings that exposures to PM2.5 are associated with decreased HRV in the elderly.

Aged↗